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Thread: caustic dispersion

  1. #1

    caustic dispersion

    Is it possible to control caustics with separate IOR values for R, G & B colour channels? This would save me a bundle of time in post, not to mention render times. Any tips on how to do this using the node editor would be great!

    BB

  2. #2
    Registered User nlightuk's Avatar
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    AFAIK, there's no way to do this with the node editor at this time, because none of the nodes allow separate R, G, and B channel output.

    I am not entirely sure how you would use the information, and why it would save time, but if someone were to write a node that did the above, then you could easily set up a gradient or some logic nodes to apply different IOR values based on the channel values coming from the colour of the surface.
    Do Placebos cause side-effects?
    If so, are the side-effects real?

  3. #3
    You could split the color into its components using 3 instances of the "Color Scalar" node. You'll find it under the Tools group. Double-click on each and set the Mode to the Color Channel you want to split-out/modify.

    If you need to bring them back together as a color - use the Make Color node.


    Yikes - i notice you are talking about controlling caustics. So splitting is not a problem - but controlling caustics would be. There is no access to Global Illumination's Caustic Intensity/Accuracy/Softnesss that I'm aware of.
    Last edited by GregMalick; 07-13-2006 at 12:30 PM.

    Somewhere, over the rainbow....

  4. #4
    Guru Meditation Sande's Avatar
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    bbuxton: Would this prism tutorial help you?

  5. #5
    Super Member Captain Obvious's Avatar
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    Nitisara has developed a shader that does chromatic abberation:

    http://www.newtek.com/forums/showthr...ight=prismatic
    Are my spline guides showing?

  6. #6
    Quote Originally Posted by Captain Obvious
    Nitisara has developed a shader that does chromatic abberation:

    http://www.newtek.com/forums/showthr...ight=prismatic
    The Prism shader is fantastic!
    I originally posted the question before the shader was ported to Mac.

    For those interested, say if you're using fPrime and can't use the shader - the long winded approach.....

    Make three renders, one for each colour channel. You should change the refraction index by a very small amount for each render, say +-0.02. You then combine the appropriate channel from each render in your compositing app or image editor. Result, nice rainbow caustics.

    Regards
    BB

  7. #7
    Super Member Captain Obvious's Avatar
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    A better way than that, bbuxton, is to animate the index of refraction and transparency color, and use motion blur.
    Are my spline guides showing?

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